Radio Frequency (RF) power amplifiers are an important part of wireless communication circuits. High power RF amplifiers are particularly important in wireless communication networks, such as for example in a base station providing wireless transmissions over a large geographic area. To communicate a greater volume and variety of content, e.g., video, wireless communications operate over increasingly broad frequency bands.
Broadband power amplifiers are of high interest in this regard. Broadband power amplifiers can support high data rate communications through wider bandwidth without the need for multiple amplifiers. Also, the small form factor of a single broadband amplifier, compared to using multiple power amplifiers for multiple bands, saves space and power, simplifies circuit layout and routing, and is otherwise beneficial. However, the optimal input and output impedances of power devices such as high electron mobility transistors (HEMT) must be matched to system impedance, which is typically 50Ω.
Impedance matching networks are frequency selective and introduce impedance dispersion versus frequency, resulting in band-limited power amplifier operation. Also, the harmonic impedances presented to devices significantly affect the device performance, and frequency dispersion results in degraded performance at a certain frequency ranges. Therefore smaller impedance dispersion of the matching networks versus frequency, and the capability of matching the optimal impedance variation range, are desirable for broadband amplifier operation.
The Background section of this document is provided to place embodiments of the present invention in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.